Lag is a common word meaning to fail to keep up or to fall behind. [1] In real-time applications, the term is used when the application fails to respond in a timely fashion to inputs.[2][3] The most common use regards online gaming when the game doesn't respond in sync with the player's controls, usually due to a slow internet connection, server latency or overworked hardware. morehttp://en.wikipedia.org/wiki/Lag